Bulk Mixing Considerations

failure modes resin is not mixed at the correct ratio improper resin ratios may lead to issues with both print quality and material properties specifics depend on the resin and how imbalanced the ratio is, but can result in decreased accuracy (increase in cure thru and overcure ) and decreased toughness or stiffness in general, stay within ± 1 5% of target component amounts for best results epu family durability is more sensitive to imbalanced mixes epx family accuracy is more sensitive to imbalanced mixes however, unless the offset accuracies would be quite small (10s of microns) unless the imbalance was greater than 5% resin is not mixed thoroughly or uniformly thorough, uniform mixing is important for best results one way to evaluate mix quality is by addition of a fluorescent dye, but this is only for establishing a thorough mixing protocol through visual inspection resin mixed with dye cannot be used for printing testing should match actual mixing conditions (container, resin volume, mix time) as closely as possible once tested, this protocol can be used moving forward, and eliminates resin waste due to burn off from cartridges testing workflow incorporate 0 1 wt% of fluorescent brightener 184 into part b cas 7128 64 5, available through sigma aldrich mix using desired method visualize with 365 nm light source (search “365nm uv flashlight”) below are examples of incomplete and complete mixing incomplete mix incomplete mix incomplete mix swirl pattern indicates components are not fully blended together complete mix complete mix complete mix absence of patterns shows components are properly blended into a uniform whole crystallization crystals may form in the part a component if it is exposed to low temperatures during shipping the following resins are subject to crystallization epu 40 epu 41 epu 43 epu 44 epu 45 epu 46 black and color base rpu 130 crystals in rpu 130 part a incubation crystals can be melted by the application of heat smaller containers (1 l, 5 l, and 19 l) can be warmed in the same oven used for thermal curing printed parts drums and ibcs require warming blankets workflow place the container of the crystallized component in the oven or incubator set the time and temperature 3 hrs at 40°c is a good starting point run the oven carefully remove the container from the oven and check that the crystals are melted if necessary, continue warming until crystals are melted carefully remove the container from the oven or incubator use caution as the container may be hot agitation of resin may be necessary before dispensing the resin, cool the container to room temperature store cartridges at the recommended temperature to prevent recrystallization consult the specific course, protocol sheet, or resin processing handout for instructions bubbles vigorous mixing may lead to the formation of bubbles in the mixed resin bubbles are typically displaced from the layer of resin that is being cured during the print process however, in extreme cases, these bubbles may be in/on the printed part and lead to mechanical or aesthetic defects surface defects are likely geometry specific and are most noticeable on cassette facing flat surfaces extreme mixing conditions and bubble formation may lead to pigment separation which will affect printability and part aesthetics unacceptable amount of bubblesacceptable amount of bubbles spraying/splashing when using an overhead mixer, high mixing speeds or mixing smaller amounts of resin may result in splashing to mitigate spraying or splashing, start mixing at low speed and be wary of splashing of part b please refer to sdss for specific hazards and warnings salting with repeated opening and closing of the stock container, the part b component can form a salt small amounts of salt may be present in mixed resin and are acceptable for printing because the salts decompose during baking large amounts of salts can result in incorrect ratios so proceed with caution if you have questions about salts in part b, reach out to carbon support acceptable levels of salt acceptable levels of salt little to no salt more salt, but only floating on the surface this will melt during thermal curing unacceptable levels of salt unacceptable levels of salt we suggest downpacking into smaller containers to minimize the chances of salting remember, part b components must be stored in uv light resistant containers, such as opaque amber nalgenes downpacking l1 tips & tricks the l1 cassette weighs at least 45 lbs always use the l1 cassette cart docid\ ibv6gvpwqutiq9fusb89 to maneuver the cassette when not in the printer two additional lab consumable accessories are recommended when printing with an l1 printer wide spatula for checking the window between prints for removing leftover resin resin transfer container optionally for dispensing when using a scale to measure dispensed resin for removing unused resin can be disposed of after use (in solid hazardous waste) note that one full cartridge is the minimum amount of resin needed in the cassette, to cover the window, throughout a print leftover resin can be transferred to an m series printer, if available, when there is enough pot life left for the resin expect more time for dispensing than with an m series printer multiple dispensers or an mmd are recommended to save time see accessories & supplies docid 95twe3ttl 5ihi6dnl4xi to purchase the items referenced above